Method for controlling ignition of an internal combustion engine

ABSTRACT

A method for controlling the ignition of an internal combustion engine ( 10 ) for a motor vehicle. More specifically, the method controls the timing of ignition for each of cylinder of the internal combustion engine ( 10 ). Control of the timing is based on two parameters, i.e., the speed at which the internal combustion engine ( 10 ) is operating and the gear in which the transmission ( 22 ) is operating. The speed is measured in terms of revolutions per minute. The gear helps to gauge what type of load may be present on the internal combustion engine ( 10 ). By identifying each of these parameters, it may easily be determined at what value the timing may be. If the specific speed of the vehicle is not located within the look-up table, where the data is stored, the method will interpolate the timing value based on values close to the value of the speed of the internal combustion engine ( 10 ) based on the neighboring values thereof.

This application claims the benefit of Provisional Application No.60/187,954 filed Mar. 9, 2000.

BACKGROUND ART

1. Field of the Invention

The invention relates to a method for controlling the ignition of aninternal combustion engine. More specifically, the invention relates toa method for modifying the timing associated with the ignition ofindividual cylinders of an internal combustion engine of a motorvehicle.

2. Description of the Related Art

Ignition control of an internal combustion engine is important toenthusiasts that want to optimize the operation of their motor vehicles.Each ignition in each cylinder must be optimized in order to maximizethe performance of an internal combustion engine.

Oftentimes, control of ignition is elaborate. Vibrations, pressures,temperatures and other parameters of an internal combustion engine aremeasured constantly. The timing of the ignition is advanced or retardedfrom top dead center depending on the measurements. The timing canchange from cycle to cycle or from operating condition to operatingcondition and the timing of the ignition is changed continually.

These types of systems are complex in design and operation. Further,these types of systems require hardware that, in many instances, must beinstalled during the manufacture of the internal combustion engine.Therefore, these systems are inappropriate for those that are seeking toimprove the performance of the internal combustion engine after it hasbeen manufactured and operated.

SUMMARY OF THE INVENTION

A method is disclosed for controlling the timing of the ignition in eachof a plurality of cylinders of an internal combustion engine that isused to power a transmission having a plurality of gears. Thetransmission is powered by the internal combustion engine through acrankshaft. The method includes the step of identifying the geartransmitting power generation from the internal combustion engine. Themethod then measures the revolutions per minute for the internalcombustion engine. The method establishes a measured revolution perminute value. The method then generates a timing parameter for ignitionfor each of the cylinders of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view of an internal combustion engine, partiallycut away, incorporating one embodiment of the invention; and

FIG. 2 is a logic diagram of one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a perspective view of an engine for a motor vehicleis generally indicated at 10. The engine 10 is an internal combustionengine. The internal combustion engine 10 may include a distributor 12or, in the alternative, it may include an electronic set-up moreappropriate for operation with an electronic fuel injector system(neither shown). The internal combustion engine 10 is controlled by anengine control unit 14. A bus, graphically represented by line 16, isused to communicate commands and data transfer between the enginecontrol unit 14, the various electronic components and sensors employedby the internal combustion engine 10. The engine control unit (“ECU”) 14provides all electrical and electronic communication between the varioussubsystems of the internal combustion engine 10 and other systems of themotor vehicle (none shown). The ECU 14 will be described in greaterdetail subsequently. The internal combustion engine 10 includes aplurality of cylinders represented in FIG. 1 by each of the electricalwires 18 that extend out of the distributor 12. Each of the cylindersincludes a piston and at least one intake and exhaust valve (noneshown). The valves are moved by a camshaft and the pistons move acrankshaft 18 as is well known in the art.

The crankshaft 18 extends into a torque converter 20, which ismechanically connected to a transmission 22. The transmission 22,partially cut away in FIG. 1, includes a plurality of gears 23, whichare selected either automatically or manually to determine theconversion of the torque generated by the torque converter 20 to therotational speed of the wheels of the motor vehicle (neither shown).

Referring to FIG. 2, a logic diagram of the method according to theinvention is generally indicated at 24. The method begins at 26. The ECU14 measures a parameter or output of the internal combustion engine 10at 27. In the preferred embodiment, the output measured is the amount ofrevolutions made per minute (RPM) by the crankshaft 18 of the internalcombustion engine 10. The ECU 14 identifies the gear 23 in which thetransmission 22 is currently operating at 28. Using the information ofwhich gear the transmission 22 is in, the ECU 14 uses a look-up table at30 to determine the timing, i.e., advance or retard, of the ignition fora particular cylinder. The look-up table includes a row of data forevery gear found in the transmission 22. In one embodiment, the tablealso includes sixteen columns. Each of the sixteen columns identifiesthe value for the revolutions per minute (RPM) of the crankshaft. It maybe appreciated by those skilled in the art that there may be any numberof gears 23 in the transmission 22 and there may be any number ofcolumns delineating graduations in revolutions per minute.

Once the ECU 14 accesses the look-up table, it determines whether thespecific RPM is represented in the look-up table. This step is performedat 32. If the specific value for the RPM is represented in the look-uptable, the timing for a particular ignition for a particular cylinder ofthe internal combustion engine 10 is generated at 34.

If the specific value for the RPM is not represented in the look-uptable, the ECU 14 collects values in cells adjacent the value closest tothe measured RPM at 36. Once these values are collected, the ECU 14linearly interpolates these values at 38 to identify a timing parameterfor the ignition at 34. The method then returns at 40 to begin theprocess again at 26. This process is done for each cylinderindependently of the others allowing spark advances or retardationsbased on the individual cylinder being fired.

The timing of the ignition for a particular cylinder is determined tooptimize the combustion characteristics of the fuel found in theparticular cylinder of the internal combustion engine 10. If the timingadvances too far, the fuel in the cylinder of the internal combustionengine 10 will detonate. Detonation is often referred to as “knock.”This phenomenon is undesired because it reduces the performance of theinternal combustion engine 10 and jeopardizes the integrity of theinternal combustion engine 10. By not advancing the timing of theignition, performance is compromised resulting in a reduced fueleconomy. By utilizing the look-up table, the timing of the ignition offuel in a cylinder can be more highly tuned wherein the tuning is afunction of the gear in which the transmission 22 is operating.Identifying the gear 23 currently being used by the transmission 22 addssophistication to the ability to time the ignition of fuel in thecylinders of the internal combustion engine 10.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology which has been used is intended to be inthe nature of words of description rather than of limitation.

Many modifications and variations of the invention are possible in lightof the above teachings. Therefore, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed.

1. A method for controlling the timing of ignition in each of aplurality of cylinders of an internal combustion engine used to power atransmission having a plurality of gears through a crankshaft, themethod comprising the steps of: identifying one of the plurality ofgears transmitting power generation from the internal combustion engine;measuring a speed of operation for the internal combustion engine bymeasuring the revolutions per minute of the crankshaft of the internalcombustion engine to establish a measured revolution per minute value;identifying timing parameters using a look-up table; determining whetherthe measured revolution per minute value is represented in the look-uptable; and generating the timing parameter for ignition for each of thecylinders of the internal combustion engine.
 2. A method set forth inclaim 1 including the step of interpolating the timing parameters frommember values of the look-up table close to the measured revolution perminute value.
 3. A method as set forth in claim 2 including the step ofcollecting values for revolutions per minute from cells in the look-uptable that are close to the measured revolution per minute value.